Muscle soreness is commonly experienced following prolonged endurance exercise, especially among recreational exercisers. Caffeine can improve endurance performance and reduce muscle pain during exercise. However, the effects of caffeine on recovery from a demanding exercise bout have not been elucidated. PURPOSE: The purpose of this study was to investigate the effects of caffeine supplementation on rating of perceived muscle soreness (RPMS) and total mood disturbance (TMD) following the completion of a 100-mile endurance cycling event. METHODS: Males (n=26; 53±10 years old) and females (n=6; 46±11 years old) who were participating in the Hotter’n Hell Hundred bicycle ride volunteered for this research study. Immediately following the ride 20 subjects, in a double-blinded randomized fashion, were provided with 3 mg/kg body mass caffeine; 12 subjects ingested identical looking placebo pills. Participants continued ingestion of their assigned pills for the next 3 mornings (i.e., ~800 hrs) and afternoons (i.e., ~1200 hrs), and abstained from all food/fluid sources of caffeine. Before the cycling event, and prior to each ingestion of pills, RPMS and TMD was assessed via questionnaires. Leg and overall RPMS were rated on a 1-to-6 scale where 1 was the absence of soreness and 6 was severe pain that limited movement. TMD was assessed using the Brunell University Mood Scale and is a combination of self-assessed fatigue, vigor, depression, confusion, anger, and tension. Differences between treatment groups over time were assessed with a two-way repeated measures ANOVA. RESULTS: Changes over time in measures of TMD and RPMS were not dependent on treatment group (i.e., non-significant interaction; p>0.050). However, the caffeine group, independent of specific day, tended to have a lower morning RPMS in the legs [0.9 ± 0.1 vs 0.5 ± 0.2 arbitrary units (AU) for placebo and caffeine, respectively; p=0.084] and overall (0.8 ± 0.1 vs 0.4 ± 0.2 AU p=0.071). The same trend for the caffeine group to have lower RPMS in the legs was present in afternoon measures (1.0 ± 0.2 vs 0.5 ± 0.2, respectively; p=0.070). Afternoon RPMS was lower overall in the caffeine group (i.e., main effect of condition; 0.8 ± 0.1 vs 0.3 ± 0.2; p=0.017). There were no effects of condition on TMD (P > 0.050) CONCLUSION: These data suggest caffeine may reduce perceived soreness following an endurance cycling event. Caffeine was beneficial when muscle soreness was assessed in the afternoon when caffeine levels were higher. Given there were some perceptual benefits to caffeine ingestion, it may be recommended that caffeine be utilized to aid in recovery from an endurance cycling event.